Manufacture of sugar



Patented Sept. 14, 1926.

UNITED STATES I 1,599,462. PATENT OFFICE.

EDUARD EKRBER, or ninrnnnnnae; G RMANY, assreNon'ro THE INTERNATIONAL seem AND ALCOHOL COMPANY LIMITED, A BRITISH COMPANY, LONDON, ENG- LAND.

No Drawing. Application filed June 15, 1925,

As is well known it is possible to produce sugar from cellulose-containing material by means of concentrated hydrochloric acid, which for the sake of briefness will hereinafter be referred to as wood-sugar, This sugar is a kind that has not yet been defined exactly, but amongst other things I proves to be a complex sugar by reason of the fact that hydrolysis is necessary to convert it into a ferment-able sugar.

Hitherto ity-has not been possible in a satisfactory manner to purify this complex sugar, i. e. to'free it from acid and other detrimental accompanying substances. Experiments by electrolysis, dialysis, and other methods have not led to a technical result. It was also not to beexpected that it would be possible for this purpose to use alkaline earths, similar to the methods known for cane sugar. Wood sugar being, as stated, a kind of sugar that hitherto has. not been examined chemically, it was not even to be presumed whether it would in fact pass into an insoluble compound with alkaline earth oxides. By reason of the sensitiveness of this sugar towards alkalies it was further tobe feared that considerable losses would be incurred by the alkali action. I

In a surprising manner it has,fhoweyer, been found that with alkaline earths it is possible to obtain a precipitation and puri-- fication of the wood-sugar by keeping within determined conditions. For this purposeit is necessary to introduce finely divided calcium oxide into the strong sugar' solution in the cold. The separated sugar-lime compound is filtered ofli and. suspended in water, is decomposed by acids 'whichform' insoluble lime salts.

For examplethe preferably 2030% sugar solution after neutralizatiom'which is preferably effected by means of calcium car- 1 bonate, is stirred up, at a temperature below 20 C., with finely powdered or, finely dispersed calcium oxide. After ashort time there separates a copious precipitateof sugar-lime compound. I After pressing and washingwith as small quantities of water as possible the moist compound is decomposed by acids, such as carbonic acid or sulphurous acidj In this manner there are obtained very pure solutions of polysaccharides without any considerable losses. If theoperation MANUFACTURE OF SUGAR.

Serial No. 37,329, and in Germany June 26, 1924.

kinds ofsugan- According to the present.

invention this is effectedby introducing water into the molecule 'of the compound, that 1s to'say it is hydrolyzed, Mineral acid is used as catalyst. The hydrolysis must be elfected u'nder-very-special conditions. The sugar is so sensitive to the action of acid at high temperatures that it is only possible to conductthe hydrolysis satisfactorily within very narrow limits of sugar and acid concentration, time and temperature. Even with very slight variations of the conditions considered as being favorable, the sugar is easily damaged or destroyed on the one hand other hand.

It is not absolutely necessary for the lime precipitation described to precede the hyd rolysis as by hydrolysis itself apartial preliminary purification takes place at the same time by subsiduary' reaction, .The. hydrolysis takes place atvarious temperatures either at ordinary or increased pressure. The selection of the kind or conditions of heating depends essentially on the nature of the origin alsubstance.

If a syrup is under consideration, which has still a relatively high content of acid, the procedure for example is as follows The syrup .is dissolved in water in such a'mannor that the concentration of syrup amounts to'about 20% and hydrochloricacid about 3%, then it is allowed to boil under ordinary pressure for about 2-2 hours.

and is not completely hydrolyzed on the 4 If however a great bulk of material, freed from acid. is available or if a neutral sugar solution has been obtained by previous treatment with lime, then hydrolysis is effected ample under ordinary pressure then not more than 25% sugar and 3% hydrochloric acid must be present in the solution as otherwise damage or destruction of the sugar and simultaneously reversions take place. *The duration of boiling depends on'the content of sugar and acid of the solutions. The concentration of sugar is chosen as high as possible in view of the further treatment of the solution which is necessary later on.

When operating under pressure according to the second example, the concentration may be at 40% and even higher, the acid content being below 1%, preferably 0.3%, in order to enable the operation to be carried out in large metal vessels. Also in this case the duration and'degree of heating-depend on the content of the solutions. About 130 C. may be regarded as the upper temperature limit.

By such hydrolytic dissociations the wood-sugar not only becomes directly fermentable but also cry'Stallizable'. Inorder to obtain crystal sugar from the hydrolyzed solutions, it is necessary first to reduce the acidity to the point of neutral reaction and their to rapidly evaporate up to a degree of concentration suitable for crystallization. If there still existed an acid reaction the evaporation. could not be effected without loss and reconversion of the sugar, and even in the case of a neutral reaction it is advantageous to efi'ect the evaporation as quickly as possible.

-A fermentable wood-sugar solution prepared in accordance with one of the two ydrolyzing processes is neutralized, for example, by carbonate of sodium. In a vacuum evaporation or even in a roll drier, such, for example as used for drying potatoes, wherein the material to be only a part of a revolution, a syrup is produced therefrom, from which the se arated chloride of sodium-is removed while 01:. If then'the' syrup has a concentration of 7 0-80 A dried is run over a hot rotating roll on which it remains for per cent by weight of sugar, it is allowed tocool and crystallize out.

It is surprising that from the solutions obtained from a number of kinds of sugar it is possible to obtain in this manner sugar in the form of crystals.

What I claim and desire to secure by Letters Patent of the United States is 1. A method for the production of pure, fermentable', and .crystallizable sugar from wood sugar, comprising, introducing a finely subdivided alkaline earth oxide into a strong, raw, wood sugar solution, separating out the resulting sugar-alkaline earthcompounds, then liberating the polysaccharides from the separated sugar-alkaline earth compounds by means of acid, which form insoluble alkaline-earth metal and ing about 40% of sugar, and an acid content up to about 1%, to about 130 C.

4. A method according to claim 1, wherein the preliminarily purified wood sugar solution is hydrolyzed by heating a solution containing 40% of sugar and an acid content of 0.3%, up to 130 C.

5. A method according to "claim 1,,w'here in the purified and hydrolyzed sugar solution is exactl neutralized, and is then evaporated rapid y to a degree of concentration suitable for crystallization.

EDUARD FARBER. 

